Reposting of article from HomeGuides.SFGate.com. They have additional articles on this topic.
Blueberries are known for their love of acidic soils, preferring a pH level of 4.8 to 5.5. If you’re discouraged from growing blueberries because of chalky or alkaline soil, take heart. Your soil can be altered both before and after planting to create and maintain the low pH level blueberries prefer. Before you purchase soil amendments — sulfur commonly used for acidifying soil — conduct a soil test to determine how much you’ll need to alter your soil.
- Work large amounts — as much as you have available — of shredded leaves or pine needles into the soil at least six months before planting blueberries. Leaves — especially oak leaves — and pine needles acidify the soil, so adding them now may lower how much sulfur you will need to add at planting time.
- Conduct a soil test about six weeks before planting your blueberry bushes.
- Calculate how many points you need to lower the pH level, based on your soil test results. If your soil’s pH is 8.0, for example, you need to lower it by at least 2.5 points.
- Lay the amount of sulfur you need on the surface of the soil, based on package instructions. The amount depends on both square footage and how alkaline the soil currently is. A 25-foot patch might require between 1 to 2 pounds of sulfur, depending on initial soil test results.
- Work the sulfur into the top 12 to 18 inches of your soil and wait several weeks before planting blueberry bushes.
- Mulch blueberry bushes with a 3-inch layer of pine needles or shredded leaves after planting; the mulch will add acidity to blueberry bushes as it decomposes.
- Reapply acidic mulch materials every year, adding at least 1 inch to the soil’s surface, depending on how much of the previous year’s mulch has decomposed.
- Test the soil’s pH level yearly. You will likely need to re-acidify your soil every two to three years.
- Top-dress your blueberry bushes with sulfur every two to three years. Rake mulch aside, set a circle of sulfur around each blueberry bush, or a straight line in front of a row blueberry bushes, and rake mulch back into place. The amount of sulfur depends on soil test results and square footage; consult package directions.
